Merge branch 'features/JAL-2608closeOverview' into develop

diff --cc src/jalview/appletgui/AlignFrame.java
Simple merge

diff --cc src/jalview/appletgui/OverviewPanel.java
Simple merge

diff --cc src/jalview/gui/AlignmentPanel.java
Simple merge

diff --cc src/jalview/gui/OverviewPanel.java
index 51d7a84,7cbe8b7..9ddb751
--- 1/src/jalview/gui/OverviewPanel.java
--- 2/src/jalview/gui/OverviewPanel.java
+++ b/src/jalview/gui/OverviewPanel.java
@@@ -350,11 -318,22 +352,25 @@@ public class OverviewPanel extends JPan
    {
      try
      {
-       av.getRanges().removePropertyChangeListener(this);
+       if (av != null)
+       {
+         av.getRanges().removePropertyChangeListener(this);
+       }
+ 
 +      oviewCanvas.dispose();
++
+       /*
+        * close the parent frame (which also removes it from the
+        * Desktop Windows menu)
+        */
+       ((JInternalFrame) SwingUtilities.getAncestorOfClass(
+               JInternalFrame.class, (this))).setClosed(true);
+     } catch (PropertyVetoException e)
+     {
+       // ignore
      } finally
      {
 +      progressPanel = null;
        av = null;
        oviewCanvas = null;
        ap = null;